If you're in the market for a way to dress up the humble spud, look no further than this easy, cheesy Potato-Fennel Gratin recipe. Packed with salty, nutty parmesan, tender potatoes and rich caramelized fennel, there's honestly nothing better. It took all of my self control not to eat the entire pan, and as a bonus, it only took me 15 minutes to assemble.
My love of spuds runs deep. Like, having a baked or mashed potato bar at my wedding-kind of love. For this decadent side, they get the star treatment with a creamy, cheesy sauce and sweet, anise scented caramelized fennel. In short, this potato fennel gratin is the perfect side for hearty holiday dishes like my smoked boneless leg of lamb or red wine braised short ribs.
But aside from just tasting magnificent, this starchy stunner is built for stress-free holiday entertaining. It requires just a few simple ingredients, can be assembled ahead of time (in just 15 minutes, no less!) and is good enough to lick the plate. Seriously, y’all. Do yourself a favor and put this yummy side on your menu!
What is Potato Gratin?
The French word gratin—pronounced "graw-TEN"—usually refers to a specific method of cooking. Generally speaking, it refers to a dish with a browned crust, most often achieved with breadcrumbs or cheese. (In some instances, "gratin" can also refer to the baking dish, which is usually oblong and shallow. That said, any casserole dish will do the trick.)
Potato gratin is simply the term for a baked casserole of sliced potatoes with a cheesy crust. It’s also known as scalloped potatoes or au gratin potatoes, but no matter what you call it, the results are incredible. I mean, is there anything better than potatoes with cheese and cream? Methinks not. Well, unless you add caramelized fennel to the mix, that is.
Jump to:
- What is Potato Gratin?
- Why You’ll Love This Easy Holiday Side Dish
- Ingredients & Substitutions
- How to Make Potato Gratin with Caramelized Fennel
- Optional Variations & Dietary Adaptations
- Expert Tips
- Storage & Reheating
- Serving Suggestions
- FAQs
- More Potato Recipes
- Potato & Caramelized Fennel Gratin with Parmesan Cheese
- 💬 Reviews
Why You’ll Love This Easy Holiday Side Dish
- Extra Special - The thing that sets this gluten free potato gratin recipe apart from any other that I've tried is the addition of caramelized fennel. Done properly, caramelized fennel adds a sweet anise flavor and lends a textural richness similar to caramelized onions.
- Speedy Prep - With fewer than 10 basic ingredients, this simple recipe is a snap to shop for. And, unlike some potato au gratin recipes, there's no need to pre-cook your potatoes. As a result, you’ll have it ready for the oven in just 15 minutes!
- Make-Ahead Magic - Whether you’re hosting a fancy dinner party, prepping for a giant Easter, Thanksgiving or Christmas feast, or just want to have a comforting side dish ready to go when you are, this meal-prep-friendly potato fennel gratin is the answer. Assemble it ahead of time, then just pop it in the oven!
Ingredients & Substitutions
As promised, you need fewer than 10 simple ingredients to make this yummy recipe for potatoes au gratin:
- Butter - Because butter makes everything better! If possible, use grass-fed organic butter for the healthiest fat profile—preferably cultured, too, for the flavor.
- Fresh Fennel Bulbs - This is the secret to making our cheesy potato gratin extra delicious. If you can’t find it, swap in yellow onions instead.
- Garlic - For sweet allium complexity. If you don’t have any fresh, use ¼ teaspoon of garlic powder per clove. And, if alliums are off the table, omit the garlic and add a few pinches of asafoetida.
- Scrap Stock or Broth - Either chicken, veggie or beef broth will work just fine. I recommend making your own broth from kitchen scraps to save money!
- Yukon Gold Potatoes - These yellow potatoes have the perfect blend of the starchiness of Russets and creamy, shape-holding qualities of wax potatoes. Plus, you don’t have to peel them!
- Parmesan Cheese - For salty, umami, nutty, cheesy yumminess. Be sure to grate your own cheese for the best melt-ability. If you’re vegetarian, make sure to check your labels—traditional parmesan is made with animal rennet.
- Heavy Cream - For added richness. Slightly lighter whipping cream can be used instead.
- Salt & Black Pepper - Just the basics. Use freshly ground black pepper for the best taste.
How to Make Potato Gratin with Caramelized Fennel
Step 1: Sweat. Melt some butter in a large skillet over medium heat. When the butter begins to bubble, add the fennel slices. Don't worry if the pan looks quite full. Much like sautéed onions, the sliced fennel will lose quite a bit of volume as it cooks. Add a hefty 5-finger pinch of kosher salt to the raw fennel to encourage sweating. Cook, stirring occasionally, until the fennel pieces are becoming a bit soft and translucent on the edges.
Step 2: Sauté. Add minced garlic and stir, cooking until fragrant. This usually takes about 30-45 seconds.
Step 3: Simmer. Add your stock or broth to the pan. Bring to a simmer, then let the magic happen. Stir occasionally over the next 10 or so minutes, until the stock evaporates. You should be left with super soft and lightly golden pieces of fennel. All liquid should be evaporated from the bottom of the pan. Taste a bit, then season with salt and pepper as necessary.
Step 4: Slice the potatoes into roughly ¼" rounds. In the bottom of your gratin dish (or casserole dish or pie plate), spread out a single layer of potato rounds. Try to fill out as much space as you can without overlapping. Sprinkle with kosher salt and fresh cracked pepper.
Step 5: Spread out the sauteed fennel mixture in an even layer, stretching it as far as possible. You want to have a little bit in each bite!
Step 6: Top with the remaining potato rounds. Season with kosher salt and pepper again.
Step 7: Add Cheese. Sprinkle the entire top of the gratin with parmesan cheese. Don't be shy! You want the end result to be bubbly, cheesy and downright decadent.
Step 8: Drizzle the heavy cream over the top. Pour it slowly, doing your best not to disturb the cheese layer. You want to cream to get in as many nooks and crannies as possible. If you're working ahead, this is a great place to stop. You can cover the gratin with foil and pop it in the fridge until you're ready to bake.
Step 9: Bake Twice. We’ll cook the gratin twice since we didn’t par-cook the potatoes. The first should be for about 45 minutes at a lower temperature (about 325ºF) with a tight covering of foil. This will trap the steam and cook them through without browning at all. Remove from the oven and check your progress. The potatoes will still be firmer than you would want to eat, but you should be able to pierce them with a fork. If they are too firm, re-cover them with foil and return the gratin to the oven.
Once the potatoes are firm-but-fork tender, remove the foil. Crank the oven to 375F, then return the gratin to the oven. Bake for another 30-45 minutes (this will depend on how many layers you have!). When the potato fennel gratin is done, the top should be golden and bubbly and the potatoes should easily yield to a fork. Rest for 5-10 minutes, then serve hot and enjoy!
Optional Variations & Dietary Adaptations
- Dairy-Free - Use vegan whipping cream and vegan parmesan for all the flavor with none of the dairy.
- Vegetarian - Make sure your parmesan cheese is vegetarian-friendly and opt for vegetable broth or stock.
- Vegan - Follow the instructions in the bullet points above to make the gratin potatoes both dairy-free and vegetarian.
- Allium-Free - Omit the garlic in favor of a few pinches of asafoetida (hing).
- Fennel-Free - Swap in caramelized onions for an equally satisfying twist. (Check out my potato-onion pierogi recipe for my best onion caramelizing tips.)
Expert Tips
- Work ahead. Caramelized fennel can be made ahead, in case you need extra lead time. It will keep covered in an airtight container in the refrigerator for up to a week, or in the freezer for up to 2 months. It’s just as versatile as caramelized onions—feel free to make extra and add it to sandwiches, omelettes or pasta for an instant flavor boost.
- Control the color. Is your potato gratin browning too quickly? Lightly tent foil over the top during the second bake to prevent too much color from developing. Just be sure not to seal the foil around the edges, or the sauce may end up watery because it won't be able to evaporate at all.
- Potato smarts. Wash and scrub your potatoes thoroughly—they grow in the dirt, so some is likely to be attached to the skins. If you're using wax potatoes, there is no need to peel them. If you opt for thick skinned russets instead, make the extra effort and peel them first. Also, be sure to remove any "eyes" on the potato and any abrasions where the potato has oxidized.
- Thinly slice your fennel bulbs so they caramelize more quickly and evenly. Cut them into vertical quarters, then slice each vertically. If you're lucky enough to have found fennel with the fronds still attached, set them aside for later. They make a pretty garnish when chopped, similar to dill and can also be saved for later.
- Evenly slice your potatoes to the same thickness so they cook at the same rate.While not necessary, a mandoline makes it easy to make perfectly even slices of potatoes and fennel.
Storage & Reheating
One of the best parts about this fennel potato gratin is that you can prep ahead and make hosting a breeze.
- Fennel Prep: Start by caramelizing the fennel in advance — it will keep in an airtight container in the fridge for up to a week, or you can freeze it for 1–2 months.
- Make-Ahead: You can also assemble the entire gratin, cover tightly with foil, and refrigerate it overnight. That way, all that’s left to do is bake it fresh the next day while you enjoy time with your guests.
- Leftovers: Once baked, the gratin will last up to a week in the fridge, though in my house it rarely makes it past day three because it’s just that good. For longer storage, freeze cooled portions in freezer-safe containers for up to 2 months.
Reheating Instructions:
- From the fridge: Cover the dish with foil and reheat in a 350°F oven until warmed through, about 20–25 minutes. Individual portions can also be reheated in the microwave for 2–3 minutes, though the oven keeps the top crispier.
- From the freezer: Thaw overnight in the fridge, then reheat following the same oven directions. If you’re short on time, you can reheat straight from frozen by covering with aluminum foil and baking at 350°F for 45–50 minutes, removing the foil for the last 10 minutes to re-crisp the top.
Serving Suggestions
My potato fennel gratin is pretty dang decadent, so I usually reserve it for the cooler months when I'm looking to food for that warm and cozy feeling. For Christmas, I'm going to pair it with my Marmite mustard smoked leg of lamb, roasted Brussels sprouts with bacon jam and Disney-style ratatouille.
That said, it'll pair beautifully with just about anything including pork roast, pork tenderloin with fall veggies, sheet pan chicken sausage dinner, chicken paillards, Dutch oven turkey breast, rack of lamb, or even a good steak dinner. And you'll hear exactly zero guff from me if you decide to serve it to yourself as a complete meal—particularly with a fried egg on top and a green salad on the side. It's honestly that good.
FAQs
While the terms are often used interchangeably, there’s a subtle difference between the two. Scalloped potatoes are typically made by layering thinly sliced potatoes with cream or milk, then baking until tender. Potatoes au gratin, on the other hand, take it up a notch by adding cheese (often Gruyère, Parmesan, or cheddar) between the layers and on top. This gives gratin its signature golden, bubbly crust.
A few common mistakes can keep this potatoes au gratin recipe from turning out its best. Using the wrong type of potato (I recommend tender wax potatoes) can result in slices that don’t soften properly, while uneven slicing leads to layers that cook at different rates. Skipping the step of sautéing or caramelizing aromatics such as onions or fennel often makes the dish watery and overly sharp in flavor. Another misstep is underseasoning—potatoes absorb a lot of salt and spices, so each layer needs attention. Too much liquid can also cause the gratin to become soupy instead of creamy, and pulling it from the oven too early leaves the potatoes chewy rather than tender. Finally, skipping a short rest period after baking means the gratin won’t have time to set, making it harder to slice and serve cleanly.
At its most basic, au gratin potatoes are made with just four key ingredients: potatoes, cream (or milk), cheese, and butter. The potatoes provide the base, the cream creates a rich sauce, the cheese adds flavor and that signature golden crust, and the butter ties everything together. Many recipes add extras like caramelized fennel ( 👋), garlic, herbs, or breadcrumbs, but those four are the essentials.
The best cheese for gratin is one that melts smoothly and adds a rich, nutty flavor. Gruyere cheese is the classic choice for plain potatoes au gratin—it melts beautifully, creates the signature golden crust and adds a hint of nuttiness. Parmesan is often added for extra sharpness and crispness on top—I personally think it pairs with the fennel better. Other good options include Comté, Fontina, or sharp white cheddar, depending on your flavor preference. Many cooks like to combine two cheeses (one for meltability and one for punchy flavor) to get the best of both worlds, so feel free to experiment!
While fresh fennel used to be more of a specialty item when I was growing up, it has definitely become more mainstream as of late. While I can only find it at my local Kroger some of the time, I know that Trader Joe's has it on display year round (albeit without the fronds attached). I also know that more upscale stores like Publix and Whole Foods almost always have some in stock. That said, if you can't find any, don't fret! This yummy potato gratin would be just as delicious with the addition of some caramelized onions, shallots or leeks in place of the fennel. The flavor will be slightly different, but you'll get a similar consistency and sweetness.
I personally love using Yukon Gold potatoes for this recipe. They're incredibly creamy and decadent tasting even before you add the cheese and cream, so they are really yummy when you add in the naughty stuff. That said, you can easily substitute any wax potatoes if Yukon Golds aren't available. You could also sub in russet potatoes if you prefer, but you'll definitely want to peel them ahead of time.
More Potato Recipes
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Potato & Caramelized Fennel Gratin with Parmesan Cheese
Ingredients
Caramelized Fennel
- 2-3 tablespoon Butter
- 2 bulbs Fresh Fennel sliced
- 6 cloves Garlic minced
- 2 C Stock or Broth I used chicken, but veggie or beef will work just fine
- Kosher Salt and Pepper to taste
To Assemble
- 2 ½ lb Yukon Gold Potatoes sliced ¼" rounds
- 4 oz Parmesan Cheese grated
- 1 C Heavy Cream
Instructions
- Remove fronds. Vertically quarter fennel bulbs, remove root base and vertically slice. Melt butter in a heavy bottomed sauté pan until bubbling. Add fennel slices and a 5-finger pinch of salt to encourage sweating. Stir occasionally, cooking until fennel is beginning to soften and become translucent, 3-4 minutes.Add garlic and stir. Cook until fragrant, 30-45 seconds.Add stock or broth and bring to a simmer. Cook, stirring occasionally, until broth is evaporated and fennel is golden and fork tender.2-3 tablespoon Butter, 2 bulbs Fresh Fennel, 6 cloves Garlic, 2 C Stock or Broth, Kosher Salt and Pepper
- In the bottom of gratin, casserole or pie dish, spread out a single layer of potatoes, attempting to cover as much of the pan as possible without overlap. Sprinkle with kosher salt and pepper.Add fennel in single layer, stretching to cover as much surface area as possible.Layer remaining potatoes atop fennel. Season with salt and pepper.Sprinkle with parmesan cheese, covering as much surface area as possible. Slowly drizzle in heavy cream, being careful not to disturb the cheese too much. Try to get the cream to touch as much as possible.2 ½ lb Yukon Gold Potatoes, 4 oz Parmesan Cheese, 1 C Heavy Cream
- Cover tightly with foil. *If you prefer, you can place the gratin in the fridge overnight to bake off for the following day.Preheat oven to 325F. Bake gratin covered for 30-45 minutes, until potatoes are still too al dente to eat, but you can push a fork through. Remove foil and crank heat to 375F. Return to oven for another 30-45 minutes, until top is golden and bubbly and potatoes are easily pierced by a fork. *If topping is browning too quickly, lightly tent foil over top while baking. Do not seal edges as you want some evaporation to take place.Allow to rest for 5-10 minutes, then serve and enjoy!
Notes
- Fennel Prep: Caramelize the fennel in advance — it will keep in an airtight container in the fridge for up to a week, or you can freeze it for 1–2 months.
- Make-Ahead: You can also assemble the entire gratin, cover tightly with foil, and refrigerate it overnight and bake from the fridge.
- Leftovers: Once baked, the gratin will last up to a week in the fridge, though in my house it rarely makes it past day three because it’s just that good. For longer storage, freeze cooled portions in freezer-safe containers for up to 2 months.
- From the fridge: Cover the dish with foil and reheat in a 350°F oven until warmed through, about 20–25 minutes. Individual portions can also be reheated in the microwave for 2–3 minutes, though the oven keeps the top crispier.
- From the freezer: Thaw overnight in the fridge, then reheat following the same oven directions. If you’re short on time, you can reheat straight from frozen by covering with aluminum foil and baking at 350°F for 45–50 minutes, removing the foil for the last 10 minutes to re-crisp the top.
- Control the color. Is your potato gratin browning too quickly? Lightly tent foil over the top during the second bake to prevent too much color from developing. Just be sure not to seal the foil around the edges, or the sauce may end up watery because it won't be able to evaporate at all.
- Thinly slice your fennel bulbs so they caramelize more quickly and evenly. If you're lucky enough to have found fennel with the fronds still attached, they make a pretty garnish.
- Evenly slice your potatoes to the same thickness so they cook at the same rate. While not necessary, a mandoline makes it easy to make perfectly even slices of potatoes and fennel.
- Dairy-Free - Use vegan whipping cream and vegan parmesan for all the flavor with none of the dairy.
- Vegetarian - Make sure your parmesan cheese is vegetarian-friendly and opt for vegetable broth or stock.
- Vegan - Follow the instructions in the bullet points above to make the gratin potatoes both dairy-free and vegetarian.
- Allium-Free - Omit the garlic in favor of a few pinches of asafoetida (hing).Fennel-Free - Swap in caramelized onions for an equally satisfying twist. (Check out my potato-onion pierogi recipe for my best onion caramelizing tips.)
Nutrition
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